Anatomy - Thorax Flashcards
What are the branches of the aortic arch
- brachiocephalic trunk (divides into right common carotid and right subclavian)
- left common carotid
- left subclavian
Describe the course of the thoracic aorta
-ascending aorta begins at aortic orifice
-ascending aorta becomes arch at level of sternal angle (T4/T5), passes supero-posterior to the left
ascends anterior to right pulmonary artery and bifurcation of trachea
passes over the root of the left lung
descends posterior to left lung root at T4 level
-arch becomes descending aorta at level of sternal angle (T4/T5)
continues to level of T12, where it exits the aortic hiatus to become the abdominal aorta
Model of clavicle: identify parts of a clavicle and demonstrate muscular attachments
- deltoid: lateral 1/3 anterior
- trapezius: lateral 1/3 posterior
- pectoralis major: medial 1/3 anterior-inferior
- sternocleidomastoid: clavicular head, medial 1/3 anterior
- subclavius: inferior middle 1/3
What are the anatomical relations of the medial 1/3 of the clavicle
medial:
sternoclavicular joint
posterior: first rib brachiocephalic vein ijv subclavian vein
Describe the course of the subclavian vein
- becomes subclavian vein from the axillary vein medial to outer border of 1st rib
- courses medially posterior to clavicle and superior to first rib
- lies anterior to anterior scalene, which separates it from the subclavian artery
- becomes brachiocephalic vein at medial border of anterior scalene, joins the IJV
CXR image: outline the structures that make up the cariomediastinal borders on a CXR
trachea = 1 aortic arch = 2 left pulmonary artery = 3 left atrium = 4 left ventricle = 5 left cardio-phrenic angle = 6 superior vena cava = 7 right pulmonary artery = 8 right atrium = 9 inferior vena cava = 10 right costophrenic angle = 11
What structures are located at the same level as the sternal angle
- bifurcation of the trachea, division of the pulmonary trunk, SVC, hila of lungs
- ascending aorta becomes arch, arch becomes descending aorta
- phrenic nerve, vagus nerve, azygous vein, thoracic duct
Describe the lobes of the lungs and their fissures
right lung:
3 lobes = superior, middle, inferior
-superior lobe separated from middle lobe by horizontal fissure
-middle lobe separated from inferior lobe by oblique fissure
left lung:
2 lobes = superior and inferior
-superior lobe separated from inferior lobe by oblique fissure
What lobes of the lung lie adjacent to right and left cardio-mediastinum
- right upper mediastinum = right superior lobe
- right heart border = right middle lobe
- left upper mediastinum = left superior lobe
- left heart border = left superior lobe
CXR image: demonstrate the lobes and fissures of the lung
- horizontal fissure: follows level of 4th costal cartilage
- oblique fissure: from T2 posteriorly to 6th costal cartilage anteriorly
How do you differentiate between RLL and RML pneumonia on CXR
right middle lobe pneumonia has loss of the right heart border
Describe parietal pleura surface anatomy
- 3cm over medial 1/3 clavicle
- comes together at T2
- diverge on left at 4th costal cartilage
- diverge on right at 6th costal cartilage
- mid clavicular line at 8th rib
- mid axillary line at 10th rib
- mid scapular line at 12th rib
- lung edge is 2 ribs higher
Identify the diaphragm and its attachments
- sternal part: attach to posterior part of xiphoid
- lumbar (crural) part: attach to medial and lateral arcuate ligaments and L1-L3
- costal part: inferior 6th costal cartilage and ribs
What are the openings of the diaphragm
- T8 = IVC, right phrenic nerve
- T10 = esophagus, vagal trunk
- T12 = aorta, thoracic duct, azygous vein
What is the nerve supply of the diaphragm
phrenic nerve (C3, C4, C5)
What is the ligamentum arteriosum
remnant of the ductus arteriosum
connect pulmonary trunk to arch of aorta, allowed blood to bypass the lungs
Model of first rib: identify and demonstrate its features and side
- head, neck, shaft, tubercle, grooves for subclavian vein and artery
- scalene tubercle for attachment of anterior scalene muscle
- relations: subclavian vessels and apex of lung
- features: broadest, shortest and most sharply curved rib
What muscles attach to the first rib
anterior/middle scalene
subclavius
intercostals
serratus anterior
What nerves are associated with the first rib
- sympathetic trunk in contact with anterior border of head
- inferior trunk of brachial plexus crosses
Describe the surface anatomy of the heart
left: 2nd costal cartilage to 5th ICS midclavicular line
right: 3rd costal cartilage to 6th costal cartilage
Describe the borders of the heart
- right: right atrium in line with SVC and IVC
- inferior: right ventricle, slightly left ventricle near apex
- left: left ventricle, slightly left auricle
- superior: great vessels and both atria
- anterior: right ventricle
- base: left atrium
What part of the heart lies directly behind the sternum
right ventricle
Describe the cardiac conduction system
- SA node: anterolaterally at junction of SVC and right atrium
- AV node: posteroinferiorly in interatrial septum near the opening of the coronary sinus
- AV bundle: comes off AV node, via fibrous skeleton, along membranous IV septum, divides into RBB and LBB
What is the blood supply of the conducting system
- SA node: RCA in 60%, LCA in 40%
- AV node: RCA in 80%, LCA in 20%
- AV bundle: LAD in most
Model of heart: demonstrate the arterial blood supply
right coronary artery:
originates from right aortic sinus and runs in coronary AV sulcus between atria and ventricles
-gives off an SA nodal branch in 60% of people
-right marginal passes inferior to apex and supplied right ventricle and apex
-posterior iv branch runs in posterior IV groove to apex, supplies RV and LV and posterior 1/3 of IVS
-AV nodal branch near origin of posterior IV artery, supplied AV node in 80% of people
-supplies: right atrium, most of right ventricle, diaphragmatic part of left ventricle, part of IV septum, SA/AV nodes
left coronary artery:
originates from left aortic sinus, runs in atrioventricular groove
-anterior IV branch (LAD) runs in anterior IV groove to apex and anastomoses with posterior IV branch of RCA
supplies both ventricles and IV septum and gives off a diagonal branch
-circumflex follows coronary sulcus around left border of heart and supplies left ventricle and gives off left marginal
-supplies: left atrium, most left ventricle, part of right ventricle, most IVC
Occlusion of which vessel will result in anterolateral STEMI
proximal LAD
Model of heart: describe the venous drainage of the heart
- coronary sinus runs left to right in posterior coronary sulcus
- receives great cardiac vein, middle cardiac vein and small cardiac vein
- drains into right atrium
Identify the structural components of the tricupsid valve
- 3 cusps (anterior, posterior and septal) attached to fibrous AV ring
- in ventricle, cusps attach to tendinous cords called chordae tendinae, which arise from papillary muscles
Describe the intercostal muscles
External intercostals:
Inferior border of rib to superior border of rib below, run inferoanteriorly
Elevate rib during forceful inspiration, supplied by intercostal nerve
Internal intercostals:
Inferior border of rib to superior border of rib below, run inferoposteriorly
Interosseous part - depresses ribs, active during expiration, supplied by intercostal nerve
Interchondral part
Elevates ribs, active during inspiration, supplied by intercostal nerve
Innermost intercostals
Inferior border of ribs to superior border of rib below
act during forced expiration
supplied by intercostal nerve
Subcostals
Internal surface of lower ribs to superior border of 2nd and 3rd ribs below
Act in same manner as internal intercostals
What muscles are responsible for respiration
- diaphragm: primary muscle of inspiration and passive expiration
- costal muscles: move ribs during forced respiration
- accessory muscles: scalene, sternocleidomastoid, pectoralis major and minor, serratus anterior
- abdominal wall muscles: active in forced expiration
Landmarks for inserting a chest drain and what layers are transversed
- anterior drain = 2nd intercostal space, midclavicular line
- lateral drain = 5th intercostal space, just anterior to midaxillary line
- layers: skin, subcutaneous tissue, external intercostals, internal intercostals, innermost intercostals, parietal pleura
- structures at risk laterally: neurovascular bundle, long thoracic nerve, lung, diaphragm, liver
Where do intercostal vessels run
-under the rib in the costal groove, in between internal and innermost intercostal muscles
ordered nerve-artery-vein from inferior to superior
-there is also a collateral vessel bundle at lower section of intercostal space
Describe the arterial supply of the intercostal space
anteriorly:
-internal thoracic artery gives rise to anterior intercostal artery
posteriorly:
-posterior intercostal arteries directly off aorta
What are the contents of the intercostal space
- muscle layer: external, internal and innermost intercostals
- vascular bundle between internal and innermost intercostals
What structures do you need to avoid when placing an internal jugular central line
- common carotid artery, apex of lung, vagus nerve, phrenic nerve, brachial plexus, trachea
- complications: line misplacement, arrhythmia, infection, thrombosis
What veins are involved in the drainage of the head and upper limb
internal jugular subclavian brachiocephalic inferior thyroid SVC
What are the branches of the subclavian artery
- first part: right vertebral artery, internal thoracic artery, thyrocervical trunk
- second part: costocervical artery
- third part: dorsal scapular artery
Describe the course of the subclavian artery
- continuation of bracheocephalic trunk, runs posterior to right sternoclavicular joint
- passes posterior to anterior scalene muscle, descends posterior to middle of clavicle
- passes over first rib to become the axillary artery
What are the branches of the thyrocervical trunk
transverse cervical
suprascapular
inferior thyroid
What are the posterior relations of the thyroid gland
cricothyroid membrane
trachea
right and left common carotid arteries laterally
What are the branches of the descending thoracic aorta
posterior intercostal arteries
esophageal artery
bronchial artery
pericardial
